I'm currently doing research and prototyping for autoloading alternatives in Zend Framework 2.0. One approach I'm looking at involves creating explicit class/file maps; these tend to be much faster than using the include_path, but do require some additional setup.

My algorithm for generating the maps was absurdly simple:

• Scan the filesystem for PHP files
• If the file does not contain an interface, class, or abstract class, skip it.
• If it does, get its declared namespace and classname

The question was what implementation approach to use.

I'm well aware of RecursiveDirectoryIterator, and planned to use that. However, I also had heard of FilterIterator, and wondered if I could tie that in somehow. In the end, I could, but the solution was non-obvious.